Highly graphited carbon-coated FeTiO3 nanosheets in situ derived from MXene: an efficient bifunctional catalyst for Zn–air batteries

Abstract

Developing high-efficiency and low-cost catalysts for the oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) is of great significance for the commercialization of rechargeable metal–air batteries. Herein, we demonstrated the construction of graphited carbon-coated FeTiO₃ (FeTiO₃@C) via in situ annealing Ti₃C₂T_x nanosheets in a rusted-reactor and its efficient bifunctional activity for rechargeable Zn–air batteries (RZABs). The electron-transport dynamics of FeTiO₃@C can be improved by using highly conductive graphited carbon derived from Ti₃C₂T_x. The FeTiO₃@C catalyst annealed at 500 °C exhibits excellent OER and ORR activities. Specifically, FeTiO₃@C shows a low overpotential of 323 mV at 10 mA cm⁻² and a small Tafel slope of 53 mV dec⁻¹ towards the alkaline OER. During the OER process, FeTiO₃@C can be partially converted into highly active iron oxyhydroxide via in situ electrochemical reconstruction, which serves as the active species. After being assembled to RZABs, it shows an open-circuit potential of 1.33 V, a high trip efficiency of 63.4% and long-time cycling stability. This work can provide a new avenue for developing bifunctional electrocatalysts for RZABs used in portable devices.